Modification of the shape and color of hair represents an important sector of modern cosmetology. The appearance of the hair can thereby be adapted both to current fashion trends and to the individual desires of the particular person. These agents are intended to bring about not only the desired color and shaping performance, but also the minimum possible damage to the hair, and by preference should in fact possess additional care-providing properties.
One skilled in the art knows of a variety of coloring systems, depending on the requirements for the coloring process, for making available color-changing cosmetic agents, in particular for the skin or keratin-containing fibers such as, for example, human hair. So-called oxidative coloring agents are used for permanent, intense colors having corresponding fastness properties. Such coloring agents usually contain oxidation dye precursors, so-called developer components and coupler components, which, under the influence of oxidizing agents or atmospheric oxygen, form among one another the actual dyes. It is therefore usual to use two-part coloring agents from which the utilization mixtures are produced only just before utilization, from a color changing preparation and an oxidizing agent preparation. These oxidizing coloring agents are notable for outstanding, long-lasting color results. For temporary coloring, it is usual to use coloring or toning agents that contain so-called substantive dyes (“direct absorbers”) as a coloring component.
In order to produce optimum coloring performance, oxidizing coloring agents as a rule require an alkaline pH for thorough coloring, in particular between pH 9.0 and pH 10.5. In addition, the application period for attractive coloring results is usually between 10 and 45 minutes. It is therefore necessary for the ready-for-use coloring agent to be formulated and packaged in such a way that the coloring agent on the one hand can readily be distributed onto the keratinic fibers to be colored, but on the other hand remains during the application time in the fibers to be colored. It is advantageous for this if the coloring agent has a specific viscosity that enables application of the agent but allows the agent to remain at the location of use. This viscosity can be established in the ready-for-use coloring agent by means of polymeric thickeners; that thickener can be contained both in the color changing preparation or the oxidizing agent preparation.
In order to enable good mixing of the color changing preparation and oxidizing agent preparation, it is advantageous if the color changing preparation and oxidizing agent preparation possess good flow properties, and if the elevated viscosity of the utilization mixture is established only after the two components are mixed. One possibility for achieving this goal is the use of polymeric thickeners whose thickening properties change with pH. The color changing preparation possesses at least an acid pH in order to stabilize oxidation dye precursors, while the utilization mixture should have an alkaline pH. If the polymeric thickener is contained in the acid oxidizing agent preparation, an anionic polymeric thickener that results in a considerable increase in viscosity at an alkaline pH is therefore preferred.
Homo- or copolymers of acrylic acid or methacrylic acid are particularly suitable as such anionic polymeric thickeners. As a rule, to establish the necessary viscosity larger quantities (usually between 2 and 5 wt %) of such polymers are needed in the utilization mixture, and thus a correspondingly even greater quantity in the oxidizing agent preparation.
Large polymer loads, however, in particular of anionic polymeric thickeners, can lead to problems when manufacturing the oxidizing agent preparations, since such elevated utilization concentrations of thickeners can result, in particular with slight fluctuations in pH, in clogs in the manufacturing systems and equipment, such as dispensing pumps and valves. As well as the savings in raw materials, it is therefore particularly advantageous to use agents that have a reduced concentration of polymeric thickeners if the viscosity of the utilization mixture is not thereby impaired.
At least one object herein is therefore to furnish a two-part oxidizing coloring agent for keratinic fibers that possesses good miscibility of the two sub-components but exhibits sufficient viscosity that the agent on the one hand can be applied easily, but on the other hand remains at the location of action during utilization and does not flow out of the fibers. It is another object to provide an agent wherein the quantity of polymeric thickeners is reduced, so that the above-described problems during manufacturing of the agents can be minimized or eliminated. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.